It is known that adamantane shows distinctive functions because of its three-dimensionally symmetric structure, where each ring is mutually stabilized. A variety of highly functionalized copolymers (copolymers having enhanced or improved functions or characteristics) can be obtained by introducing a hydroxyl group into adamantane, and, if necessary, deriving it into an acrylic acid derivative or a carbonate. There have been suggested many processes for producing copolymers from a hydroxyl group-introduced adamantane, such copolymers including polyesters (Japanese Patent Application Laid-open No. 21090/1975 (JP-A-50-21090), etc.), polycarbonates (U.S. Pat. No. 3,594,427, etc.), polyamides and polyimides (U.S. Pat. No. 3,832,332, etc.), polyurethanes (Japanese Patent Publication No. 12891/1969 (JP-B-44-12891), etc.), polysulfones and polysulfonates (U.S. Pat. No. 3,753,950, etc.), vinyl polymers (Japanese Patent Publication No. 28419/1971 (JP-B-46-28419), etc.), and the like.
The polymers obtainable from adamantane derivatives, which generally have excellent functions or characteristics (high functionality), are by far superior to conventional polymers in optical characteristics such as small light-inducing loss, high refractive index and double refraction index, and other characteristics including moisture-resistance, heat-resistance, coefficient of thermal expansion, etc. Accordingly, there have been some attempts to make use of these polymers as optical fibers, optical elements, optical lenses, holograms, optical discs, contact lenses and other optical materials, transparent resin coating compositions for organic glasses, electric conductive polymers, photosensitive materials, fluorescent materials and so forth.
Incidentally, an amino derivative derived from an alcohol derivative of adamantane is useful for introducing various medicines having excellent pharmacological activity or agricultural chemicals, such as "SYMMETREL" (trade name), a therapeutic agent for Parkinson's disease.
As described above, hydroxyl group-containing adamantanes, particularly adamantanepolyols having hydroxyl groups at plural bridgehead positions, are utilized in a broad range of applications.
Japanese Patent Publication No. 16621/1967 (JP-B-42-16621) suggests the use of chromic acid for the production of a group of adamantanepolyols. According to this process, an adamantanediol can be obtained, almost quantatively, from adamantane in a single step. However, this process requires an excess amount of expensive chromic acid and complicated post-treatments. Besides, even under severe reaction conditions, it is difficult to produce an adamantanetriol or a higher adamantanepolyol.
Japanese Patent Publication 26792/1967 (JP-B-42-26792) discloses a process which comprises oxidizing a molten adamantane with oxygen using a cobalt salt catalyst for the production of an adamantanediol. However, its selectivity is critically low, and a higher conversion causes the formation of by-products such as ketone derivatives. Additionally, this literature teaches a process for separating and purifying an adamantanediol from the reaction mixture, based on the fact that the adamantanediol has a different degree of solubility in a hydrocarbon or ether from that of the other components (e.g. by-products, raw materials).
In Japanese Patent Application Laid-open No. 196744/1990 (JP-A-2-196744), a tribromoadamantane is hydrolysed to give an adamantanepolyol. In this process, however, it is difficult to produce a tribromoadamantane. Besides, since the tribromoadamantane is lost in the hydrolysis step in a large quantity, the yield of an adamantanetriol is miserably low.
Japanese Patent Application Laid-open No. 38909/1996 (JP-A-8-38909) discloses a process comprising oxidation of a substrate with oxygen using an imide compound catalyst. By oxidizing a substrate such as adamantane, according to this process, monools, diols, triols, tetraols and other polyols of adamantane can be produced at a high conversion and selectivity even under mild or moderate conditions. However, it is extremely difficult to separate, in an efficient manner, these adamantanemonool, adamantanediol, and adamantanepolyols among themselves, as each of them has closely similar chemical properties to those of the others.